Radar antenna for transmission/reception of radar waves at measuring of a level of a surface of a liquid, wherein the liquid is contained in a tank, for example a tank on vessel, at a process manufactory or at an oil refinery. More specifically, the invention is aimed at minimizing disturbances from fluids, for example water condensed on the radar antenna.
When measuring a level of a surface of a liquid by means of a radar and its adherent radar antenna, wherein said liquid is contained in a tank, e. g. a tank on a vessel, at a process manufactory or at an oil refinery, different fluids may be present, whereby the fluids absorb or stop the propagation of the radar waves.
By level measuring by means of a planar antenna belonging to prior art technology the radar waves are transmitted out from the planar antenna from radar wave emitting elements, such as patches, in a right angle from the plane surface of the planar antenna.
The object of the invention is to solve some of the problems mentioned above.
This is achieved by means of a device according to claim 1.
By providing a radar antenna used for transmission and reception of radar waves, when measuring a level of a liquid contained in a tank, for example a tank on a vessel or a tank at an oil refinery, with a sheet arranged in the path of the transmitted radar waves, that is between the antenna and the liquid, and by arranging a surface of said sheet facing the liquid in an angle inclined in relation to the horizontal plane, this implies that a fluid occuring on the surface, for example condensed water, is drained off from the surface by means of gravity. The sheet is preferably arranged directly on the antenna on the surface of the planar antenna.